Structural analysis of an inversion controlling sex determination in the Hessian fly

The Hessian fly (Mayetiola destructor ) has an unusual mechanism of sex determination where the X:A ratio is fixed post-zygotically instead of at fertilization. The maintenance or elimination of the paternally derived X chromosomes during embryogenesis is controlled by a maternal sex determination factor (MSDF). Genetic analysis has demonstrated that MSDF is perfectly associated with an inversion (Inv1) on the long arm of chromosome A1. Inv1-lacking females produce only males and Inv1-carrying females produce only females. To identify MSDF, the DNA sequence of Inv1 is being determined by integrating information obtained from the BAC-end sequences (BES) of BAC contigs in Inv1 and the assembly of Hessian fly genome sequence generated by 454 sequencing. Thus far, results show that Inv1 is greater than 1.6 Mb in length. A comparison of the inverted and non-inverted sequence within this region of the genome has been initiated.